Molecular cloning and sequence analysis of cDNA encoding plasma alpha-1-antiproteinase from Syrian hamster: implications for the evolution of Rodentia.

Complementary DNA clones encoding plasma alpha-1-antiproteinase (also called alpha-1-antitrypsin or alpha-1-proteinase inhibitor) were isolated from Syrian hamster liver cDNA library and sequenced. The deduced amino acid sequence of putative reactive site (P3-P'3) was Ile-Pro-Met-Ser-Val-Pro, characteristic of alpha-1-antiproteinase of orthodox type (Suzuki, Y. et al. (1991) J. Biol. Chem. 266, 928-932). A molecular phylogenetic tree of all known orthologous proteins was constructed based on the synonymous substitution rate. The result shows that the hamster has branched off first before the divergence among mice, rats, and gerbils, and that the rabbit is the closest relative of the guinea pig which is separated from the rodents. Although this tree differs largely from the classical phylogeny based on the morphology (hamsters and gerbils belong to the same family, Cricetidae, and the guinea pig belongs to the order Rodentia), it lends support to recent concepts that the hamster and guinea pig differ, in a number of biochemical features, not only from each other but also from mice and rats, and that the guinea pig may belong to an order distinct from Rodentia.